Improvement in the manufacture of paper



v UNITED. STATES PATENT OFFICE.

VIIENRYV nlunnnrornor' ALLEGHENY CITY, PENNSYLVANIA.

lMPROVEMENT INTHE. MANUFACTURE, OF PAPER.

Specification forming part of Letters Patent No. 165,594, dated July 19, 1870.

To all whom it may concern:

Be it known that I, IIENRYPEMBERTON,-Of Allegheny City, State of Pennsylvania, have invented a new and useful Improvement in the Manufacture of Pape; andfI do hereby de clare the following to.- be a full, clear, and exact description of the same, which will enable others skilled in the art to which it appertains to practice my invention.

In manufacturing many varieties of paper,

it is desirable to incorporate into the texture of the'paper a greater or lesser amount of nonorganized .or mineral matter, partly for the purpose of cheapening the fabric thus produced byfthe substitution of the cheaper nonorganic material for the more expensive organic tissue, and partly for obtaining a harder,

firmer, and more opaque paper than can be produced when the comparatively soft, elastic, and transparent vegetable or animal fibers are alone made use of.

The substances. thus employed (apart from alum, rosin, and other sizings, whose action is superficial only) may be divided into two classesfirst,,those natural-or artificial inorganic materials the structure of which is either aniorphous,'or, if crystalline, consisting of extremely minute crystals, whose transverse and conjugate diameters are equal, or, at least,

inwater, and possessing the desirable-shade or absence of color, are yet in other-respects very imperfectly adapted to the requirements of the paper-makers, since their particle's, if in a sufficiently fine state of division to be fitted for incorporation into the body of the paper, are, owing to the absenceof all fibrous structure, incapable of beingproperly interwoven through and among the fibers of the organic tissues that constitute the pulp of true paper. Consequently these mineral matters are only imperfectly taken up by the fibrous pulp with'which they are mechanically agitated, a largeproportion, often seventy-five (75) per cent. of the quantity used, escaping through-the meshes of the wire-gauzein the paper-machines upon whose surface the web of fibrous tissue is deposited, while the nonfibrous earthy matter is carried away, in great part, by the escaping water. Aportion of the mineral substances is, however, retained by the paper. Even this portion, however, is so imperfectly entangled among the tissues of the paper that it readily dusts out, particularly from unsized printin g-papcr, and becomes a source offi reat annoyance and injury to the pririter, besides rapidly wearing down the faces of the type, owing to the hard an d gritty which-they are subjected to cleanse and disintegratc them deprives them of the fibrous character by breaking orv grinding up the needle-like crystals.

It is therefore 01115 by artificial or chemical means that it becomes possible to obtain nonorganic matters thatposse'ss, with the required cheapness, whiteness, purity, and fine state of division, also'the desired fibrous crystalline condition. These conditions are combined in the crystals of hydrated sulphate of lime, (OaOSO +2-HO,) which are obtained either from the natural sulphate (gypsum) by calcination and subsequent hydration under the circumstances appropriate for the formation of a finely-divided crystalline powder, (term 7 01b0,) or by precipitation from a soluble salt of lime by sulphuric hydrate, or by some other soluble sulphate. The latter form of the calcic.

sulphate is particularly adapted to the fabrication of paper, and has, in common with other cheaper but less-fibrous forms thereof, become an important article of commerce. Much disappointment has arisen, however, when these preparations have been employed by papermakers, by the yield of paper being Very far below what should have been produced from the sum of rag or other pulps used and of the calcic sulphate added, notwithstanding that the water escaping from the engine was perfectly clear, and free from all traces of suspended particles, while, under the same circumstances, if Ohina clay had been used in place of the sulphate, the water would have been verymilky, and loaded with finely-divided and suspended clay, the loss of which would be evident.

This disappointment and loss by the use of the calcic sulphate arises. however, from a different cause'viz, the solubility of sulphate of lime in water, by which a large quantity of the sulphate is removed from the pulp, and is lost, quite or absolutely, as if it had possessed no fibrous structure, one part of it being soluble in about four hundred and fifty (450) parts of water. This loss has prevented, to a great extent, the employment of the above salt, that, in other respects, possesses every requisite to recommend it to the paper-maker.

I have invented a means by which this loss can be avoided, and for which invention I ask that Letters Patent may be granted to me.

My invention is essentially as follows:

It is a well-known principle in chemistry that, when a substance is brought in contact with water or other fluid for which it possesses chemical afiinity, (or solubility,) the fluid in question willunite with or dissolve only a certain quantity. After this quantity is dissolved, the remainder, in however great excess itmay be to the fluid in question, remains, and behaves preciselyas an insoluble substance would do if brought in contact with the said fluid. If, therefore, a saturated solution of sulphate of lime was employed in place of pure water in effecting the admixture of the fibrous sulphate with the paper-pulp proper, it is evident that no-further loss of calcie sulphate by solution could occur. l

. .1 My invention consists in employing, in the manufacture of paper, wherein sulphate of lime enters as an ingredient, the saturated or partly-saturated solution of sulphate of lime in place of ordinary water, whether the said solution is obtained'by collecting the water escaping from the paper-machines, (in which calcic sulphate has been used or employed a second time,) orby purposely and intentionally making in a separate vessel a saturated or partly-saturated solution of sulphate of lime, and then using the same, or by producing in the hollander or other part of the paper-ma chine a saturated or partly-saturated solution of calcie" sulphate by adding some other and cheaper form of sulphate of lime, soas to saturate, in part or whole, the Water used in the manufacture of the paper before the illtroduction of the more expensive and more fibrous artificially-prepared sulphate of lime. All or any of these methods produce the same results, and I claini the use of all or any of them, as circumstances may render most expedient. I

In order to permit others skilled in the art to avail themselves of my invention, I will now describe the method I prefer to use in de tail, without, however, confining myself thereto, but making use of any of the above-described plans as may be most expedient.

I first prepare a large tank or other reservoir of such capacity as may furnish a full and ample supply of water for the use of the paper-machines, hollanders, and other apparatus, (preferring, however, not to use the contents of said reservoirs for the supply of the steam-boilers, nor for the solution and pre-- paration of the soda or alkaline solutions used in the-manufacture of paper.

To such a reservoir (being empty) I adapt a.

small agitating-tank, with such stirring maehinery therein as may serve to keep its contents in brisk intercommunication, and so that its contents may be slowly butuniformly discharged into the larger reservoir, and through which all the water entering thelarger reservoir must pass. Intothis smaller tank, being filled with water, I introduce, in fine powder, sulphate of lime, either in the form of ground gypsum, (native,) or, preferably, calcined ground plaster-of-paris, in the proportion of one pound of sulphate to every six (6) cubic feet of water entering said tank. This proportion may be decreased after some time, according to the size of the reservoir and to the amount of deposit of undissolved sulphate that has accumulated on .the bottom thereof; but it should never. be less than one pound of sulphate to four hundred pounds of water. After the reservoir is filled it should be left at rest until the undissolved sulphate has had time to settle, when the clear solution may be drawn off and used. Or the sulphate may be introduced in lumps into the reservoir, and so used.

For some purposes it may be more convenient to add to the water in the hollander the requisite quantity of calcic sulphate, either in the form of ground plaster, or, for better qualities of paper, in the form of term alba, be-

fore the introduction of the more expensive and more fibrous variety of sulphate; or all the water escaping from the machines may becollected in a suitable reservoir and returned to the original reservoir and be worked over and over again. These modifications may be rendered desirable by circumstances; but I give the preference to the plan hereinbefore described. 7

By the use of this process it is easy to incorporate fifty pounds of the fibrous sulphate with one hundred pounds of rag-pulp, and to obtain therefrom one hundred and fifty pounds of excellent paper, whereas, without the use of my invention, not over one hundred and five pounds, or at the utmost one hundred and ten pounds, would have been produced. For making inferior quality of paper, as much as pound for pound can be used to advanta e.

liaving thus described my invention, what I claim, and desire to secure by Letters Patent, is-

The application of a saturated or partly.

saturated solution offlsulphate of lime to the manufacture of paperlwhereiu sulphate of lime, under any name, enters as an ingredient, 1

whether. said solution hasibeen prepared,

first, previously in aseparate vessel or reservoir, or, secbnd obtained by the introduction into any part of the'proce'ss of a cheaper ,or less-fibrous form of sulphate previous tuthe introduction of the more fibrous and more expensive form of the sulphate desired tube in: corporated, or,- lastly, by the recovery and re use of the saturated or partly-saturated solutionof sulphate of lime that has already passed .through and-escaped from the apparatus. 1 i HENRY PEMBERTON v 5 Witnesses:- a a Hmmsou E. DAVIS,

A. I-. Pmmnn'rolr. 

